Joint sealing devices



3, 1968 YOSHIKI FUJIHARA 3,396,640

JOINT SEALING DEYICES 2 Sheets-Sheet 1 Filed April 25. 1966 FIG.6

FIG.8

g- 13, 1968 YOSHIKI FUJIHARA 3,

JOINT SEALING DEVICES Filed April 25, 1966 2 Sheets-Sheet 2 United States Patent 3,396,640 JOINT SEALING DEVICES Yoshiki Fujihara, Lyons, Ill., assignor to W. R. Grace & C0., Cambridge, Mass., a corporation of Connecticut Filed Apr. 25, 1966, Ser. No. 545,109 7 Claims. (Cl. 94-18) ABSTRACT OF THE DISCLOSURE An expansion and contraction joint for concrete structures which comprises two opposed strips preferably of stainless steel, a tubular, flexible joint-sealing element interposed between the strips and fastened to each strip by the engagement of its inturned upper marginal flange on each strip with outwardly directed beads formed on the sealing element.

This invention relates to joints in concrete structures, particularly pavements, slabs, aprons, and floorings, and provides a method and means of making expansion and contraction joints whereby the tedious job of hand-fiinishing the joint is eliminated.

The sealing element which is disclosed in the following specification is adapted for any of the above uses merely by making its dimensions appropriate to the thickness of the concrete and to the expected movement between the concrete elements. As the preferred example of such joint seals, a seal for an expansion and contraction joint between concrete highway slabs will be disclosed.

Concrete pavements expand and contract. The movement of a pavement which experiences a 120 F. temperature differential during the year varies from 0.158 inch when the payment slab is 20 feet long, to 0.475 inch when the slab is 60 feet long.

It is conventional to place into fresh concrete highway pavement some form of divider strip; such as, metal, wood, plastic, or asphaltic compositions to predetermine the contraction cracking of the concrete as it sets up and starts its expansion and contraction cycle. In the case of a contraction joint, these strips are inserted vertically at preselected locations and extend from the surface of the highway down to a depth of about ,6 of the thickness of the pavement. In the case where each section of highway pavement is terminated with an expansion joint, the pre-molded strips are inserted vertically and extend from the subgrade of the highway to a depth of to of the thickness of the concrete below the intended highway surface. If load-transferring devices such as dowels are to be used, the dowels are fitted through holes punched in the filler strip. After pouring the concrete, the pavement is floated, usually by a machine-driven float, and machinefloating is then followed by floating with a bull float. Thereafter each joint is separately hand-finished, for it is necessary that the margins of the joint be straight and true and free of any breaks or projecting bits of aggregate which overlap the joint space.

The principal objects of this invention are to produce a presealed expansion or contraction joint which will expand and contract with the seasonal movement of the highway slabs and maintain a tight, sealed joint, protected against the penetration of dirt, sand, and water; to produce a joint, which, once installed either by a jointplanting machine or by hand, permits all main components to be left in place; to provide a joint which eliminates the step of packing or pouring a distortable filling into the joint space, and, in a preferred form, to produce a joint which will maintain sharp, clean margins which require no hand finishing; to produce a joint which permits the surface of the highway to be floated either by machine or by hand, without regard to the presence of FCC divider strips and without the requirement that some component first be removed.

In brief summary, the invention comprises two especially contoured metallic strips, the upper margins of which grip a rubber expansion member. Each strip incorporates means to anchor it to the transverse margin of its adjacent concrete slab. Tie means hold the strip in compressed or collapsed condition (which is the condition of the strip at the time of its installation), and margin-retaining means top the assembly. These means not only maintain straight, true margins which require no hand finish, but prevent the float from filling the joint with cement paste, or dragging small bits of rock across the face of the joint.

The invention is best understood by reference to the accompanying drawings, and from the following specification in which FIG. 1 is a perspective view of one form of the joint strip as ready for planting in the concrete;

FIG. 2 is a perspective view of the opposed metallic elements;

FIG. 3 is a vertical section through the joint between two concrete slabs showing the joint in collapsed condition;

FIG, 4 is a vertical section through the joint of FIG. 2 as it appears in winter when the slab is fully contracted;

FIG. 5 is a perspective view of the rubber expansion element;

FIG. 6 is an enlarged detail showing the presealed joint strip provided with a compressible sponge margin-maintaining element; and

FIGS. 7 and 8 show possible modifications of the vertical walls of the sponge.

Referring to the figures, the joint assembly, 10 comprises two opposed metallic strips, 11 and 12 (see FIG. 2), preferably made of stainless steel. Each strip has a channel-beam configuration and comprises an upper flange, 13, an upwardly and outwardly directed lower anchoring flange, 14, and a web, 15.

Web, 15, is distorted so that the lower portions, 16- 15, of the opposed strips may abut, while the upper portions, 17-17, of the web, 15, are bent outwardly to provide housing space for the tubular rubber sealing element, 18, which is locked in position by the in-turned margins, 19-19, of the strips, 11 and 12.

intermittently, wall-anchoring loops, 27-27, are formed in the upper portion, 17, of the web, 15, by cutting parallel slits through the web and out-thrusting the intervening metal, Loops or protruding tabs, 27, together with anchoring flange 14, bed in the concrete and hold each of the metallic strips, 11 and 12, permanently in position.

The sealing element, 18 (see FIG. 5), is a tubular extrusion of tough, age and ozone resistant rubber, having an upper wall, 21, and a lower wall, 22, of generally chevron shape. Upper wall, 21, extends beyond the side walls, 23-23, and terminates in a head, 24, which fits within the recess formed by the in-turned margins, 18-18, of

the strips, 11 and 12, and the upper portion, 17, of the web, 15.

A centrally located diaphragm, 25, extends between the upper wall, 21, and the lower wall, 22. It should be understood that the dimensions which follow may be varied to accord with the differing specifications, but a generally satisfactory joint for highway use is formed when the depth of the strip from topsurface to anchoring flange is from to the depth of the concrete pavement, and if the rubber sealing strip has the following expanded dimensions:

Width between side walls when expandedfi-inch Thickness of side walls and central web- ;-inch Thickness of top wall -inch Overall depth-1 inch Dip of chevron in the top wall -iuch Dip of chevron in the bottom wall -inch- The joint is assembled by placing the two strips, 11 and 12, in opposed relationship and inserting the beads, 24, in their marginal recess, which then may be crimped down on to the rubber.

Following assembly, the strip is collapsed and is maintained in this condition by tie-wires, 2e46, which are bound about it. To prevent displacement of the tie-wires in shipment, they are passed through the loops or between the protruding tabs, 2727. When the joint is collapsed, the rubber folds in as shown in FIG. 3, the two side walls, 2323, coming in contact with the central diaphragm, 25.

Tu this condition, the strips are supplied to the highway contractor, who inserts the assembled divider strip transverse to the highway at distances ordered by the highway specification. The strips are so placed that their top margins will lie at or just below the surface of the pavement. The location of these strips when the concrete hardens is permanent, for they are anchored firmly to the end of the concrete slab by the anchoring flange, 14, and the loops or tabs, 2727.

The divider strips, the length of which equals the full Width of the highway pavement, may be inserted in the wet concrete by hand or, better, by a joint-planting machine which, at the predetermined slab length, vibrates the divider into position. The concrete above the divider is hand finished to prevent any irregular spalling along the edges.

The finishing step usually is confined to brushing out whatever cement paste has been forced into the open fold of the seal, 18, and cutting the tie-wires. Thereafter, the joint is free to follow the contraction of the slab as the concrete hardens, and move with whatever temperature change occurs.

This joint seals the space between highway slabs between the two extremes of complete collapse of the pre-sealed contraction joint (FIG. 3), at summer temperatures, and separation when exposed to the low temperature of winter (FIG. 4). The working distances through which a joint such as has been described will operate are from complete contact to a relatively wide separation. The rubber which, as before stated, may be any of the tough ozone and chemically resistant types, makes the joint proof against the ingress of water, sand, and dust, which otherwise can pack into the joint space, and because the joint is permanently sealed, the seal will not bulge if the subg-rade has proper drainage.

Although the pre-sealed joint just described is highly useful, and requires merely the cutting of the tie-wires-and brushing cement paste out of the fold of the collapsed sealthe addition of a toplayer of sponge rubber gives added cost savings and improvement. This form of the invention is shown in FIG. 6.

In this modification, the next step in assembly is to adhere a sponge rubber margin-retaining strip, 28, to the top surface of the upper flanges, 13. The adhesion of the sponge to the metal may be secured by any convenient means, but normally is accomplished by a pressure-sensitive layer which is coated on the lower face of strip, 28.

As in the previous case, the sponge-covered presealed joint is planted transverse to the roadway either by hand or by a jointaplanting machine to a depth which will leave at least a major portion of the vertical walls, 29, of the rubber sponge projecting above the intended surface of the pavement.

Commonly, highway pavements are finished in operations performed in the following order: concrete is poured and leveled between the screeds, the surface is then smoothcd by a machine-driven float. Following machine-float ing, temporary divider strips are inserted in the wet concrete. Following the insertion of the temporary divider 4 strips, the pavement is finished by a bull float; then, when the concrete is sufiiciently set, the temporary divider strip is removed, and the joints are made straight and true by hand finishing.

When the float passes over the projecting portion of the rubber sponge, the sponge compresses far more easily than fresh concrete moves. Accordingly, the main action of the float is to compress the sponge sufliciently to allow the float to pass over it and to sweep off excess concrete from the top surface of the sponge. As soon as the float has passed beyond the pavement joint, the sponge rubber expands to its full thickness, and establishe and maintains a straight margin as the concrete hardens. The sponge rubber is removed after the concrete has achieved its initial set, and cutting of the tie wires should be done immediately thereafter.

Desirable thicknesses of sponge are approximately A of an inch. Open-cell sponge having a density of from 2 to 10 lbs. per cubic foot will be found suitable. In describing open-cell sponge, the term rubber has been used in a generic sense to denote a compressible and elastic substance. The actual material may be rubber, artificial rubbers such as chlorobutadiene, butadiene-styrene, and =acrylonitrile types, isobutene with isoprene or butadiene, ethylene-proplyene, polyurethanes, polyethylene sponge, and polyethylene-vinyl acetate mixtures.

The vertical margins, 29, of the sponge rubber may be given a reverse contour to that which is required for the end-contour of the highway slab. FIGS. 7 and 8 show, respectively, flaring and curved contours which will appear in reverse along the margins of the concrete slab. Whatever contour for the edge finish is chosen, it must flare outwardly from the upper margin of the steel strips, 11 and 12.

Because the only attention which must be given to the joint is to remove the sponge rubber and cut the tie-wires, a very substantial cost in the laying of the :highway is eliminated.

A further and important advantage flows fromthe fact that it is not necessary to limit the length of concrete pavement to be laid in a day by the number of hand finishers available on the job to finish the joints before the concrete hardens. Pavement laying can progress without limit to the number of joints which must be made.

It is possible to utilize other materials than stainless steel for the metal in the strip, and ordinary steel is a possible substitute, but the use of salt and chloride on the highways makes a corrosion-resistant material such as stainless steel highly desirable and much less expensive throughout its years of use.

What is claimed is:

1. A joint for concrete structures, comprising two oppositely-faced metallic strips, each of said strips having an upper flange comprising out-turned flange and inturned marginal portions, a lower, upwardly and outwardly directed anchoring flange, and an intermediate web, a flexible, distortable sealing element interposed between said strips, said sealing element having upper, lower, and side walls, the said upper wall extending oppositely beyond each side wall and terminating at each upper wall margin in an outwarly directed bead, each of said beads being crimped between the out and in-turned portions of said upper flanges, thereby to maintain a permanent flexible seal between said metallic strips.

2. A joint as claimed in claim 1 wherein the configuration of the said tubular sealing element is generally rectangular, and wherein the top and bottom walls of said element are chevron-shaped, and wherein the sealing element is tubular and is divided by a vertical diaphragm.

3. A joint as claimed in claim 1, wherein means are provided to anchor the metallic strips to the concrete, and include a plurality of metallic projections directed ou-twardly from said webs.

4. A joint as claimed in claim 1, wherein the Web is provided at spaced intervals with parallel, horizontal slits,

and wherein the metal between said slits is thrust outwardly, thereby to form a loop.

5. As an article of commerce, the pre-formed joint as claimed in claim 1, wherein the sealing element is held in compressed condition between the said metallic strips by removable tie wires, said joint being preformed.

6. A joint for concrete highways, comprising two oppositely-faced metallic strips, each of said strips having an upper flange comprising out-turned flange and inturned marginal portions, a lower, upwardly and outwardly directed anchoring flange, and an intermediate web, a flexible, distortable sealing element interposed betwen said strips, said sealing element having upper, lower, and side walls, the said upper wall extending opopsitely beyond each side wall and terminating at each upper wall margin in an outwardly directed bead, each of said beads being crimped between the out and in-turned portions of said upper flanges, thereby to maintain a permanent flexible seal be tween said metallic strips, and a concrete margin-retaining element comprising a strip of sponge rubber extending unin terruptedly along the joint and adhered to the exposed upper flanges of said joint by a pressure-sensitive adhesive.

7. A joint as claimed in claim 6, wherein the concrete margin-maintaining element is secured to a backing member formed of fibers, and wherein the said fibers are secured to the said upper flanges of said metallic strips by a pressure-sensitive adhesive.

References Cited UNITED STATES PATENTS 1,885,391 11/1932 Thompson et a1. 94 18.2 3,038,395 6/1962 Middlestadt 94-18 JACOB L. NACKENOFF, Primary Examiner. 

